Different types of replaceable bulbs are commonly used as light sources in automotive headlights. As in many other applications, lamps employing light emitting diodes (LEDs) as light sources have been introduced for replacing the more traditional light sources.
Automotive headlight applications are typically associated with regulations on the provided light output and/or the lifetime of the light sources employed. A goal for the design of a LED-based lamp for automotive headlight applications may for example be to provide a light output resembling the light output of a replaceable headlight bulb which the LED-based lamp is to replace. The need to obtain a desired light output and/or a desired lifetime imposes restrictions on the design of LED-based lamps intended for automotive headlight applications. Other factors which may influence the design of LED-based lamps may for example include energy efficiency, reliability and/or cost efficiency.
JP 2011066307 A discloses a light emitting device provided with a connector, a columnar element, axially extending from the connector and provided with LEDs, and a reflective element. The reflective element prevents the light from exiting the device directly in the axial direction.
WO 2007/005003 A1 discloses a light emitting device with a columnar element, axially extending and provided with LEDs, and a transverse reflector.